Enhanced transmission through the subwavelength magnetic slits

According to the standard diffraction theory, apertures much smaller than the wavelength of electromagnetic waves transmit poorly. But it's observed experimentally that the transmission through arrays of subwavelength metallic structures exhibits peaks at some wavelengths. These properties implies novel applications including dynamic optical subwavelength filters, optic switches, and subwavelength optical fiber couplers. In this paper, we theoretically investigate the transmission of electromagnetic waves through subwavelength magnetic slit arrays. The calculated results show that the transmission can be enhanced at wavelengths without exciting surface polaritons. This enhancement is attributed to the slit-perpendicular surface current induced by the incident electromagnetic waves. Additionally, the position of the enhanced peaks shifts to longer wavelengths and the strength of the peaks exhibits more complicated properties with increasing the permeability of the magnetic material constructing the gratings.